This application incorporates herein by reference in its entirety the disclosures of U.S. Pat. No. 7,403,860, issued Jul. 22, 2008, and U.S. Published Application No. 2006/0169039, published Aug. 3, 2006.
Fueling environments typically store fuel in large storage tanks located beneath the ground, sometimes referred to as “underground storage tanks” (UST). To comply with environmental laws, rules, and regulations, these storage tanks may be double-walled and equipped with various leak detection sensors and inventory reconciliation systems. One popular leak detection sensor is sold by Veeder-Root Company of 125 Powder Forest Drive, Simsbury, Conn. 06070, the assignee of the present application, under the name “The MAG Plus Inventory Measurement Probe” (Mag Probe). This probe is typically matched with a tank monitor, such as the TLS-350R, also sold by Veeder-Root Company. Such probes measure a height of fuel within the storage tank and may optionally measure a height of water (if present). The measurements are reported to the tank monitor for usage by the operator of the fueling environment to evaluate and reconcile fuel inventory and/or detect leaks, as is well understood.
While the United States has many rules and regulations relating to leak monitoring within fueling environments, other locales have additional requirements for fueling environments. For example, countries such as India and Russia have seen a rise in fraud at fueling environments, and have consequently taken steps to combat such fraud. Specifically, these countries have become aware that dilution of the fuel within storage tanks may be used as a technique to defraud a customer. One way in which the diluted fuel is created is through the addition of alcohol to the fuel storage tank. The alcohol allows the water at the bottom of the fueling tank to mix with the fuel, and the diluted mixture is then dispensed as normal through the fuel dispensers.
To combat this fraud, some governments have mandated that fuel density be measured. If the density is outside of a predetermined allowable range, it may be inferred that the fuel has been adulterated. Even if some countries or governments do not have such legislation requiring measurement of fuel density, some fuel distribution companies that operate service stations may nonetheless find it desirable to monitor the density of their fuels for quality control purposes.
Density measurements also assist in calculation of the mass of fluid within a storage container. Differences in mass may be used to perform leak detection for fluids in situations where normal volume detection techniques are inadequate (e.g., waste oil storage containers). These situations create additional demand for density measuring devices.